The Simpsons Treehouse of Horror collection includes 4 episodes from different seasons. I'll list them by number and summarize each of the stories.

 

1) V

1) The Shinning: a parody of The Shining. The family is keeping up Mr. Burns’ lodge over the winter. Homer is stuck with no beer and no cable which drives him crazy – perhaps even crazy enough to kill.

2) Time & Punishment: In a story reminiscent of Ray Bradbury, Homer travels through time. As he changes the past he is greeted with unexpected results in his own time. This is one of my favorites as we see what would happen if Flanders ruled the world or if the Simpsons were a well-to-do family.

3) Nightmare Cafeteria: The cafeteria is running out of meat and the detention hall is over-crowded. The mutual solution? Sloppy Jimbo sandwiches. I hope cannibalism doesn’t make you want to upchuck.

 

2) VI

1) Attack Of The 50ft Eyesores: The giant billboard people come to life and ravage the town of Springfield. Can Homer give up his giant donut to save them? 

2) Nightmare On Evergreen Terrace: a Nightmare on Elm Street parody with Willie in the role of Freddy. The Simpsons kids must find a way to beat him on his own turf – their dreams. While many of the jokes in this one are classic, the ending is lame.

3) Homer3: (as in cubed). Homer is pulled into an alternate dimension… the third dimension. See Homer and Bart rendered in 3D! His family tries to save him until he is sucked into a black hole. Not really a Halloween story, but the most unique animation ever featured on the show.

 

3) VII

1) The Thing And I: Marge and Homer are keeping a dark secret hidden in the attic, one that will leave Bart scarred for life.

2) The Genesis Tub: Lisa accidentally creates life during a science project. The people think she is God and Bart is the devil. They advance enough scientifically to shrink Lisa to their size and bring her into their world, but now she’s stuck and at Bart’s ignorant mercy. 

3) Citizen Kang: Kang & Kodos assume the form of Bill Clinton and Bob Dole and run against each other for president. Homer takes it upon himself to rescue the politicians from the alien spacecraft prison when nobody will heed his warnings.

 

4) XII

1) Hex & The City: Homer ticks off a gypsy who curses the Simpson family. Weird things start happening so Homer is advised to catch a leprechaun. The little Irishman is supposed to be able to lift the curse, but it doesn’t go as planned. The Leprechaun voice in this one is annoying.

2) House of Whacks: In a tale that reminds me of Dean Koontz's Demon Seed, the Simpsons' house is fully automated and computerized with a personality set to imitate Pierce Brosnan who quickly develops an obsession for Marge. The house decides to kill Homer and take Marge for itself.

3) Wiz Kids: A Harry Potter parody. Wizards in training Bart and Lisa face off against the evil Montymort who wants Lisa's advanced magical abilities for himself.